30 replies to this topic

[whistler]

Anyone know why the stub stack for a HS6 and a HIF44 is different? Is it the bolt holes or ???

[nicklouse]

Will not fit as the holes are totally different.

[whistler]

Oh well, that answers that. Wonder why, as so many of us use HIF44s, stub stacks are so thin on the ground. I can only find the MED one for £25 plus £10 p&p! 

[MRA]

Oh well, that answers that. Wonder why, as so many of us use HIF44s, stub stacks are so thin on the ground. I can only find the MED one for £25 plus £10 p&p! 

 

You want stub stacks I make them for various classic cars,..  in billet alloy, the question is what colour do you want ?

 

PS my avatar is one of my rear brake bearing caps in polished aero grade aluminium.

Edited by MRA, 27 February 2016 - 11:26 PM.

[whistler]

Oh well, that answers that. Wonder why, as so many of us use HIF44s, stub stacks are so thin on the ground. I can only find the MED one for £25 plus £10 p&p! 

Just had an email back from MED Engineering saying that the £10 postage for a stub stack is correct as they use Interlink as a courier. Perhaps they should use Parcel2go or even Royal Mail instead for a more competitive price because there's no way am I paying £10 for a small jiffy bag.

[Mini Manannán]

Let them know they're losing a sale Whistler, that is a stupid price. I got 4 tyres delivered from Minispares for £6!

[Cooperman]

When I fitted stub stacks on my 'S' I had previously just put a radius on the carb mouth and opened up the hole in the K & N conical filter to match. I was surprised that when on the rollers it didn't seem to have improved either power or torque, although I think the throttle response might have been a bit better.

 

Then, when I fitted 1.5:1 roller-tip rockers instead of the original

'S' rockers I gained all of 2 bhp at 5700 rpm and over, nothing below that, and I think I lost a bit of bottom end torque.

 

All a bit strange when you read of the alleged gains from either or both of these mods.

[Dusky]

When I fitted stub stacks on my 'S' I had previously just put a radius on the carb mouth and opened up the hole in the K & N conical filter to match. I was surprised that when on the rollers it didn't seem to have improved either power or torque, although I think the throttle response might have been a bit better.
 
Then, when I fitted 1.5:1 roller-tip rockers instead of the original
'S' rockers I gained all of 2 bhp at 5700 rpm and over, nothing below that, and I think I lost a bit of bottom end torque.
 
All a bit strange when you read of the alleged gains from either or both of these mods.

I think I recall vizard saying that the hif carbs are superior in flow and don't really need a stubstack because they have the radius on the air filter side?
Ill have to dig through the book when Im home :)

[Cooperman]

Mine are twin H4. The inlet mouth radius is about 2mm.I matched the stubs accurately and was surprised at no measurable improvement.

[whistler]

Let them know they're losing a sale Whistler, that is a stupid price. I got 4 tyres delivered from Minispares for £6!

I did and they offered as a one off to reduce postage to about £6.55 but can't post until Friday when someone goes out for parts.

 

Mr. MRA is looking at the possibility of turning one for me.

[Mini Manannán]

I felt that my engine came 'on song' a bit earlier when I fitted a Pipercross substack to mine, 200 or 300 rpm lower, about ~3600.

[MRA]

At the air velocities that you can get get with an engine sucking through a HIF44 the mouth radius needs to be greater than 20mm this is to negate the effects of what is known as "vena contracta" ....  https://en.wikipedia.../Vena_contracta

 

Measurable differences will not often show up on a rolling road as a ram pipe will increase torque not maximum BHP.

 

The concept is simple you are looking to get minimal flow separation, by reducing turbulence and thus increasing laminar flow, think TOLL booth......

[MRA]

I felt that my engine came 'on song' a bit earlier when I fitted a Pipercross substack to mine, 200 or 300 rpm lower, about ~3600.

 

That would be because of the torque improvements

[Dusky]

My RR measures torque too tho...

Physics, I MEAN MAGIC, in carbs are the reason I started studying physics :)

Edited by Dusky, 29 February 2016 - 04:16 PM.

[MRA]

They all measure torque, but most (older ones) deliver a bhp figure only.  and sadly (probably due to cost) most operators only seem to work towards max bhp and not spend a great deal of time at the lower rev range